Minor and trace element incorporation into branching coral Acropora nobilis skeleton     

Kotaro Shirai  Tatsunori Kawashima  Tsuyoshi Watanabe  Naoto Takahata  Yuji Sano 《Geochimica et cosmochimica acta》2008,72(22):5386-5400

Chemical and isotopic compositions of the Acropora nobilis skeleton were analyzed at various spatial resolutions to investigate the mechanism by which elements are incorporated into the skeleton. Chemical and isotopic profiles along growth axes of axial and radial corallites did not show seasonal variation, with the exception of the δ¹⁸O profile of the axial corallite. Detailed observations of the skeletal structure revealed that the skeletal density increased with distance from the tip because secondarily precipitated aragonite (here called the “infilling” skeleton) filled pore spaces in the “framework” skeleton. Microscale element analyses revealed that main part of the infilling skeleton had lower Mg/Ca and higher Sr/Ca and U/Ca than the framework skeleton. At microscale, Sr/Ca and U/Ca were positively correlated with each other, and negatively correlated with Mg/Ca but only weakly. The results showed that the infilling skeleton differed significantly from the adjacent framework skeleton in terms of not only formation chronology but also chemical composition, and that the bulk composition was influenced by the infilling/framework skeletal ratio. In order to use the Acropora skeleton as a paleoclimate archive, the relationship between environmental factors and the chemical composition of each skeletal component needs to be established.  相似文献   

Landfill development in the urban fringe of Metro Manila     

Yuji Hara  Kazuhiko Takeuchi  Armando M. Palijon  Akinobu Murakami 《GeoJournal》2008,71(2-3):127-141

In low-lying areas of urban and suburban regions in Asia, the use of landfill has allowed urban land use to encroach onto watery landforms, such as back marshes, which were formerly used as rice fields. To improve understanding of the associations between land-use patterns and landfill development, we carried out a case study in the urban fringe of Metro Manila in the Philippines. We examined landfill volume derived from land-use change using GIS, and field surveyed qualitative aspects of the landfill used. We calculated the rate of application of landfill in low-lying housing development areas to be 5.0 × 10³ m³ km^?2 year^?1, most of which consisted of offsite disposal of construction waste or crushed rock produced by urban development and renewal on the adjoining uplands. The flow of fill material from offsite sources to onsite landfill development areas was on the basis of individual agreements between suppliers and developers.  相似文献   

Petrogenesis of greenstones from the Mino–Tamba belt, SW Japan: Evidence for an accreted Permian oceanic plateau     

Yuji Ichiyama  Akira Ishiwatari  Kazuto Koizumi 《Lithos》2008,100(1-4):127-146

Permian greenstones in the Jurassic Mino–Tamba accretionary complex, southwest Japan, are divided into three distinct series on the basis of their geological occurrence, mineralogy, and geochemistry. A low-Ti series (LTS) is associated with Lower Permian chert and limestone, and is the most voluminous of the three series. The LTS shows slightly more enriched geochemical and isotopic characteristics than MORB. A transition series (TS) is mainly associated with Lower Permian chert, and has more enriched geochemical signatures than MORB. Its isotopic characteristics are divided into enriched and depleted types. A high-Ti series (HTS) occurs as sills and hyaloclastites within Middle Permian chert and as dikes intruding the TS. Some HTS rocks have high MgO contents. The HTS is characterized by enrichment in incompatible trace elements and an isotopic composition comparable to HIMU-type basalt. The geochemistry of the voluminous LTS is similar to that of the oceanic basalt series of the Kerguelen plateau, suggesting production by partial melting of a shallow mantle plume head below thick oceanic lithosphere in Early Permian time. We infer that the TS formed simultaneously at the margins of the mantle plume head. In contrast, the HTS may have resulted from partial melting of a deep mantle plume tail in Middle Permian time. Permian greenstones in the Mino–Tamba belt may have thus formed by superplume activity in an intra-oceanic setting. Given the presence of two known contemporary continental flood basalt provinces (Siberia and Emeishan) and some accreted oceanic plateau basalts, the vast magmatism of the Mino–Tamba oceanic plateau suggests a large-scale superplume pulse in Permian time. Accretion of oceanic plateaux may have played an important role in the growth of continental margins and island arcs in Japan and elsewhere in the circum-Pacific region.  相似文献   

An Actively Controlled Wind Tunnel And Its Application To The Reproduction Of The Atmospheric Boundary Layer     

Cao Shuyang  Akira Nishi  Kimitaka Hirano  Shigehira Ozono  Hiromori Miyagi  Hiromori Kikugawa  Yuji Matsuda  Yasuo Wakasugi 《Boundary-Layer Meteorology》2001,101(1):61-76

An actively controlled wind tunnel equipped with multiple fansand airfoils has been developed, mainly for the purpose of reproducing the atmospheric boundary layer (ABL) for wind engineering applications. Various fluctuating flows can be achieved in this wind tunnel by altering the input data of the fans and airfoils through computer control. In this study, the ABL is physically simulated in this wind tunnel, and particular attention ispaid to the simulation of the profile of Reynolds stress. The method of generating the fluctuating flow and the experimental results of reproducing the ABL are presented. As the results show, the spatial distribution of Reynolds stress is satisfactorily simulated, and the profiles of other statisticalturbulent parameters, such as mean velocity, turbulent intensity, integral scale and power spectrum are successfully reproduced simultaneously.  相似文献   

Sound velocity and elastic properties of Fe–Ni and Fe–Ni–C liquids at high pressure     

Soma Kuwabara  Hidenori Terasaki  Keisuke Nishida  Yuta Shimoyama  Yusaku Takubo  Yuji Higo  Yuki Shibazaki  Satoru Urakawa  Kentaro Uesugi  Akihisa Takeuchi  Tadashi Kondo 《Physics and Chemistry of Minerals》2016,43(3):229-236

The sound velocity (V _P) of liquid Fe–10 wt% Ni and Fe–10 wt% Ni–4 wt% C up to 6.6 GPa was studied using the ultrasonic pulse-echo method combined with synchrotron X-ray techniques. The obtained V _P of liquid Fe–Ni is insensitive to temperature, whereas that of liquid Fe–Ni–C tends to decrease with increasing temperature. The V _P values of both liquid Fe–Ni and Fe–Ni–C increase with pressure. Alloying with 10 wt% of Ni slightly reduces the V _P of liquid Fe, whereas alloying with C is likely to increase the V _P. However, a difference in V _P between liquid Fe–Ni and Fe–Ni–C becomes to be smaller at higher temperature. By fitting the measured V _P data with the Murnaghan equation of state, the adiabatic bulk modulus (K _S0) and its pressure derivative (K _S ^′ ) were obtained to be K _S0 = 103 GPa and K _S ^′  = 5.7 for liquid Fe–Ni and K _S0 = 110 GPa and K _S ^′  = 7.6 for liquid Fe–Ni–C. The calculated density of liquid Fe–Ni–C using the obtained elastic parameters was consistent with the density values measured directly using the X-ray computed tomography technique. In the relation between the density (ρ) and sound velocity (V _P) at 5 GPa (the lunar core condition), it was found that the effect of alloying Fe with Ni was that ρ increased mildly and V _P decreased, whereas the effect of C dissolution was to decrease ρ but increase V _P. In contrast, alloying with S significantly reduces both ρ and V _P. Therefore, the effects of light elements (C and S) and Ni on the ρ and V _P of liquid Fe are quite different under the lunar core conditions, providing a clue to constrain the light element in the lunar core by comparing with lunar seismic data.  相似文献   

Peridotite xenoliths from the Shiribeshi Seamount,Japan Sea: insights into mantle processes in a back-arc basin     

Yuji Ichiyama  Tomoaki Morishita  Akihiro Tamura  Shoji Arai 《Contributions to Mineralogy and Petrology》2016,171(10):86

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Implementation of integrated multi-channel analysis of surface waves and waveform inversion techniques for seismic hazard estimation     

Abd el-aziz Khairy Abd el-aal  Yuji Yagi  Heba Kamal  kamal Abdelrahman 《Arabian Journal of Geosciences》2016,9(4):322

In this study, an integrated multi-channel analysis of Surface Waves (MASW) technique is applied to explore the geotechnical parameters of subsurface layers at the Zafarana wind farm. Moreover, a seismic hazard procedure based on the extended deterministic technique is used to estimate the seismic hazard load for the investigated area. The study area includes many active fault systems along the Gulf of Suez that cause many moderate and large earthquakes. Overall, the seismic activity of the area has recently become better understood following the use of new waveform inversion method and software to develop accurate focal mechanism solutions for recent recorded earthquakes around the studied area. These earthquakes resulted in major stress-drops in the Eastern desert and the Gulf of Suez area. These findings have helped to reshape the understanding of the seismotectonic environment of the Gulf of Suez area, which is a perplexing tectonic domain. Based on the collected new information and data, this study uses an extended deterministic approach to re-examine the seismic hazard for the Gulf of Suez region, particularly the wind turbine towers at Zafarana Wind Farm and its vicinity. Alternate seismic source and magnitude-frequency relationships were combined with various indigenous attenuation relationships, adapted within a logic tree formulation, to quantify and project the regional exposure on a set of hazard maps. We select two desired exceedance probabilities (10 and 20 %) that any of the applied scenarios may exceed the largest median ground acceleration. The ground motion was calculated at 50th, 84th percentile levels for both selected probabilities of exceeding the median.  相似文献   

The Application of GIS in Education Administration: Protecting Students from Hazardous Roads     

Fatemah Admadi Nejad Masouleh  Yuji Murayama  Todd Wendell Rho'Dess 《Transactions in GIS》2009,13(1):105-123

Though enrolment by proximity is an official educational policy in Iran, the lack of clearly defined school attendance areas has resulted in an informal open enrolment system where parents may choose public schools outside their residential areas. Two major consequences of parental choice are longer commutes to schools and increased use of motor vehicle transport. To delineate school attendance areas for public female junior high schools in the city of Rasht in Northern Iran, this research used the multiplicatively weighted Voronoi diagram (MWVD) technique to construct school attendance areas. The approach was shown to be useful in developing countries like Iran where accident fatalities are not only disproportionately high but the public school system lacks sufficient educational diversity to offset the societal costs of opting out of neighbourhood schools. A GIS-based specialist package was used for constructing the proposed school attendance areas. Given the MWVD utility in demarcating spaces so that all journeys within them are closest to a chosen point, the research concluded that proposed school attendance areas can result in shorter and more convenient commutes on foot for students. This can eliminate the need to travel by vehicle for the overwhelming majority of students and thus make their journeys more convenient and safer.  相似文献   

A GIS Approach to Estimation of Building Population for Micro-spatial Analysis   总被引：4，自引：0，他引：4  

KoKo Lwin  Yuji Murayama 《Transactions in GIS》2009,13(4):401-414

Population data used in GIS analyses is generally assumed to be homogeneous and planar (i.e. census tracts, townships or prefectures) due to the public unavailability of building population data. However, information on building population is required for micro-spatial analysis for improved disaster management and emergency preparedness, public facility management for urban planning, consumer and retail market analysis, environment and public health programs and other demographic studies. This article discusses a GIS approach using the Areametric and Volumetric methods for estimating building population based on census tracts and building footprint datasets. The estimated results were evaluated using actual building population data by visual, statistical and spatial means, and validated for use in micro-spatial analysis. We have also implemented a standalone GIS tool (known as 'PopShape GIS') for generating new building footprint with population attribute information based on user-defined criteria.  相似文献   

Compressibilities of MnFe2O4 polymorphs     

Lijin Ye  Shuangmeng Zhai  Xiang Wu  Chaowen Xu  Ke Yang  Yuji Higo 《Physics and Chemistry of Minerals》2015,42(7):569-577

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